Passive volcanic degassing often occurs at active but not actively erupting volcanoes. Gases are emitted by fumaroles and through diffuse soil degassing. This results in the emission of toxic gases such as H₂S at quasi-steady rates over long periods of time (months to years). Whilst less apparent than gas emissions during more vigorous and violent paroxysms, the long duration of emission and the fact that such gases are dispersed at low altitude (i.e. along the flanks of the volcano, often at human height) means that even the typically low concentrations (e.g. tens of ppb H₂S) pose a significant hazard to human health in nearby habitations.

La Soufrière de Guadeloupe has been undergoing an unrest phase since 1992 and it has one of the highest gas emission rates of any volcano in the Lesser Antilles. Gas emissions here are principally from three fumarolic sites at the summit though the typically high winds and low gas temperatures result in a laterally dispersed plume within a few metres of the ground. In this study, gas dispersion from the volcano over the period 2016–2021 was modelled using a numerical code that takes into account wind direction and strength, atmospheric stability, local topography and gas flux measurements; we used information from local meteorological stations, ECMWF Climate Reanalysis data and the gas flux dataset acquired by MultiGas measurements during the mentioned period.  We ran c.100 individual simulations of the most frequently observed wind and gas flux conditions using a Monte-Carlo scheme. From the ensemble of results, we calculated the mean (i.e. most probable gas concentration values at any given location) and found that the most exposed zones are the hamlet of Matouba and the upper parts of St. Claude. We also simulated particular dates with strong H₂S odours reported by local inhabitants via online surveys and we compared the model results with the Gwad’air agency’s air quality station located at St Claude, the closest town to the volcano. This allowed us to establish the prevalence of gases coming from La Soufrière in nearby cities and the accuracy of our models. The resulting maps of the areas potentially long-term (>8 years) exposed by gas emissions can be used to evaluate health risks for all people living around the volcano. In these locations, our results suggest that there is a 20% and 5% probability, respectively, for these areas of exceeding H₂S guidelines for long-term gas exposure (70 ppb).

How to cite: Rave Bonilla, Y. P., Jessop, D., and Moune, S.: Numerical modelling of the volcanic plume dispersion from  La Soufrière de Guadeloupe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-251, https://doi.org/10.5194/egusphere-egu23-251, 2023.

After the Tajogaite eruption at Cumbre Vieja volcano (La Palma, Canary Islands), volcanic gas hazard continues to affect the inhabited coastal areas of Puerto Naos and La Bombilla, as well as the nearby agricultural fields, which are located about 6 km distance from the eruptive vents. This gas hazard is primarily due to CO₂ (Hernández et al. 2022) and persist during the post-eruptive phase of the eruption. According to long-term geochemical studies conducted by INVOLCAN, the high levels of CO₂ emissions in these coastal areas were first recorded approximately three weeks before the end of the Tajogaite eruption on December 13, 2021.

To monitor this anomalous diffuse CO₂ degassing at La Bombilla, 46 surveys consisting of approximately 84 sampling observation sites have been regularly conducted since December 2021, covering an area of 0.033 square kilometers. In-situ measurements of soil CO₂ efflux and ground temperature as well as collection of samples of the soil gas atmosphere at a depth of 40cm for chemical and isotopic analysis were carried out at each sampling site. Soil CO₂ efflux measurements have been performed following the accumulation chamber method. Soil gas chemical analysis were carried out by means of a microGC and the carbon isotope ratio of soil gas CO₂ (expressed as δ¹³C-CO₂ ‰ vs. VPDB) was analyzed also in our geochem lab by a Thermo Finnigan MAT 253 mass spectrometer. Spatial distribution maps have been constructed following the sequential Gaussian simulation (sGs) to evaluate the spatial distribution of the soil CO₂ efflux measurements and quantify the diffuse CO₂ emission from the studied area. Observed soil CO₂ efflux values ranged from <0.5 (detection limit) to 449,500 gm^-2d^-1 with a mean value of 513 gm^-2d^-1. Diffuse CO₂ emission values ranged between 4.0 and 170 td^-1, with an average value of 16 td^-1. δ¹³C-CO₂ values ranged between -8.63 to -4.31 (‰ vs. VPDB) with an average value of -5.68 (‰ vs. VPDB). The temporal evolution of the diffuse CO₂ emission rate at La Bombilla shown a rapid initial decrease from the first survey (170 td^-1) remaining relatively stable between 55 and 4 td^-1. Since November 2022, the time series seems to show a progressive decreasing trend. However, the temporal evolution of the δ¹³CO₂ values shows that volcanic-hydrothermal contribution to these diffuse emanations continues to be important. In order to evaluate other potential geochemical parameters as indicators of a possible mitigation of this problem related to the CO₂ hazard, we are investigating the temporal evolution of the La Bombilla / Cumbre Vieja diffuse CO₂ emission ratio normalized per area unit.

Hernández, P. A., Padrón, E., Melián, G. V., Pérez, N. M., Padilla, G., Asensio-Ramos, M., Di Nardo, D., Barrancos, J., Pacheco, J. M., and Smit, M.: Gas hazard assessment at Puerto Naos and La Bombilla inhabited areas, Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.

How to cite: Hernández, P. A., Melián, G. V., Rodríguez, F., Álvarez Díaz, A. J., Padilla, G. D., Asensio-ramos, M., Barrancos, J., Calvo, D., Padrón, E., González Pérez, A. M., and Pérez, N. M.: CO2 hazard monitoring in the inhabited area of La Bombilla (La Palma, Canary Islands) by means of diffuse degassing studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3931, https://doi.org/10.5194/egusphere-egu23-3931, 2023.

The recent eruption of Tajogaite volcano occurred between September and December 2021 at La Palma Island is considered the most devastating of Europe since that of Vesuvio in 1944. The post-eruptive period is being characterized by the appearance of high outdoor and indoor CO₂ concentrations at inhabited areas such as La Bombilla and Puerto Naos (Hernández et al., 2022), forcing the eviction of numerous homes. However, anomalous concentrations of CO₂ have not only appeared in inhabited areas, but also in cultivated lands. In fact, the highest CO₂ concentration values measured in the outdoor environment during the entire post-eruption period have been in a banana plantation of approximately 4,200 m² that INVOLCAN has been monitoring since June 2022, named Las Hoyas.

Since June 2022, 26 scientific observation surveys have been carried out at Las Hoyas consisting of the measurement at 39 homogeneously distributed sites of the CO₂ and O₂ concentration at two heights, 40 and 170 cm from the ground, as well as sampling of atmospheric air in 19 sites at 40 cm for carbon isotope ratio of air CO₂. Air CO₂ and O₂ concentrations are measured with a hand portable Dräger X-am® 8000 meter and the carbon isotope ratio of air CO₂ (expressed as δ¹³C-CO₂ ‰ vs. VPDB) is analyzed at ITER/INVOLCAN lab by a Thermo Finnigan MAT 253 mass spectrometer. Spatial distribution maps have been constructed following the sequential Gaussian simulation (sGs) to evaluate the spatial distribution of the air CO₂ concentration. Observed air CO₂ concentration values ranged from air value (412ppm) up to 69%, the highest ever measured during the post-eruptive period, with an average value of 7.1%. Air O₂ concentration values ranged between 7.9% to air value (20.9%), with an average value of 19.2%. δ¹³C-CO₂ values ranged between –8.90 to -2.66‰, with an average value of -4.87‰, indicating a clear volcanic-hydrothermal origin for the anomalous CO₂ emitted from Las Hoyas banana plantation and ruling out a single biogenic origin.

In order to investigate the temporal evolution of the observed high CO₂ concentrations in Las Hoyas, a Sinclair statistical graphic analysis was applied to the data from each survey. Time series of background and peak populations does not show a clear trend, with the occurrence of peaks and valleys throughout the entire series, and maintaining values much higher than those of the air. Likewise, the temporal evolution of the δ¹³C-CO₂ values shows a trend towards heavier values, indicating that the volcanic-hydrothermal contribution increases with time. The spatial distribution of the air CO₂ concentration measured at 40 cm shows that in most of the surveys, the anomalous values (>10%) are located mainly along the walls of Las Hoyas and in the NW sector, where in more than a year after the eruption, the banana plants are still withered and dead terrestrial and aerial fauna constantly appear due to poisoning and suffocation from CO₂ inhalation.

Hernández et al. EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.

How to cite: Melián, G. V., Hernández, P. A., Rodríguez, F., Alvárez Díaz, A. J., Padilla, G. D., Asensio-Ramos, M., Barrancos, J., Calvo, D., Padrón, E., González Pérez, A. M., and Pérez, N. M.: Anomalous CO2 concentrations of volcanic origing in the ambient air of banana plantations at La Palma, Canary Islands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4411, https://doi.org/10.5194/egusphere-egu23-4411, 2023.

Carbon dioxide (CO₂) is colorless, odorless and also heavier than air, which means it can accumulate at low elevations. At high concentrations, CO₂ can be hazardous and can cause asphyxiation by reducing the amount of oxygen available to breathe. In high concentrations, it can also irritate the eyes, nose, and throat. During the post-eruptive phase of Tajogaite eruption, high concentrations of air CO₂, up to 20% (200,000 ppmv), have been detected both outdoor and indoor of buildings at La Bombilla and Puerto Naos, which are located about 5 km from the eruption vent. Hazardous CO₂ concentrations were detected not only in the basements, but also on the ground floors and even inside of some upper floors buildings in Puerto Naos. In the case of La Bombilla, relatively high CO₂ concentrations were just observed on the ground floors. The spatial distribution of these hazardous indoor CO2 concentrations is not uniform throughout both populated areas (Hernández et al, 2022).

In order to study and assess this volcanic hazard, in both evacuated neighborhoods, an instrumental network for air CO₂ monitoring has been established by INVOLCAN in collaboration with the DGSE-GOBCAN and the Universities of the Azores (Portugal) and Düsseldorf Applied Sciences (Germany). The first CO₂ monitoring station was installed on 9 January 2022 and by the time being this network consists of 35 air CO₂ monitoring stations with different full scale (2 of 100%, 22 of 20%, 7 of 5% and 4 of 4%). In the case of La Bombilla the air CO₂ monitoring network consists of 10 different stations monitoring the indoor (7) and outdoor (3) CO₂ concentrations, respectively. The other 25 stations are located in Puerto Naos to monitor the indoor (21) and outdoor (4) ambient air CO₂ concentrations.

Observed outdoor CO₂ maximum and mean daily average concentrations > 5% (> 50,000 ppmv) and 0.9% (9,000 ppmv), respectively, have been recorded at Puerto Naos. However, indoor CO₂ monitoring at Puerto Naos have reached maximum and mean daily average concentrations about 20% (200,000 ppmv) and 12% (120,000 ppmv), respectively. In the case of La Bombilla, outdoor CO₂ measurements have reached maximum and mean daily average concentrations > 5% (> 50,000 ppmv) and about 2% (20,000 ppmv). Stations to monitor the indoor air CO₂ concentrations at La Bombilla were just installed (December 2022) and by the time being are recording maximum and mean CO₂ concentrations about 6% (60,000 ppmv) and 1.9% (19,000 ppmv), respectively. Most of the air CO₂ monitoring stations, both outdoor and indoor, shows that the daily averages of CO₂ concentrations from fifteen-minute data during the night are usually higher than during the day.

To mitigate the observed hazardous CO₂ concentrations some remediation techniques have been suggested, such as the installation of an indoor air CO₂ monitoring network with a larger number of stations and an automatic alert system for air CO₂ concentration inside residences with forced air ventilation systems.

Hernández P. A. et al., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.

How to cite: Padilla, G. D., Barrancos, J., Hernández, P. A., Álvarez Díaz, A. J., Pérez, N. M., González Pérez, A. M., Santana, J. M., Pacheco, J. M., Viveiros, F., Weber, K., and Vilches Sarasate, J.: Air CO2 monitoring network in the urban areas of Puerto Naos and La Bombilla, La Palma, Canary Islands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4188, https://doi.org/10.5194/egusphere-egu23-4188, 2023.

Carbon dioxide (CO₂) is a gas that is found in small amounts in Earth's atmosphere. It is released into the atmosphere by volcanoes, but it is typically diluted to low concentrations very quickly and is not harmful to people or animals. However, in certain stable atmospheric conditions, cold CO₂ gas can flow into low-lying areas and reach higher concentrations. At these concentrations, CO₂ can be dangerous. If the air contains more than 3% CO₂, it can cause symptoms such as headaches, dizziness, increased heart rate, and difficulty breathing. At concentrations above 15%, CO₂ can quichly lead to unconsciousness and death. The boundary between healthy air and lethal gas can be extremely sharp; even a single step upslope may be adequate to escape death.

Since the Tajogaite eruption ended on December 13, 2021, high concentrations of CO₂ up to 20% have been observed inside the buildings of La Bombilla and Puerto Naos (La Palma, Canary Islands).  Anomalous concentrations of CO₂ are detected mainly in the ground-floor and basement of the buildings in Puerto Naos, and their distribution is not homogeneous or uniform throughout the Puerto Naos area (Hernández P.A. et al, 2022).  Because of the ultradilute nature of CO₂ in the atmosphere, chemical sorbents with strong CO₂-binding affinities are typically employed for CO₂ capture. For this study, we set up a network of 45 alkaline traps stations located on the ground-floor (streel level) inside buildings of Puerto Naos. These chemical sorbents were made up KOH 1.2 M and replace weekly. The aim of this study was to distinguish between indoor areas that had high levels of CO₂ in their alkaline traps and those with lower levels of CO₂. This was done through weekly surveys conducted from May to October 2022 in order to identify and define areas with the greatest CO₂ hazard. The statistical analysis of the results shows that 75% of the variance of the amounts of CO₂ retained weekly in the alkaline traps seems to be related to an endogenous CO₂ source while 25% of the variance observed is related to external variables.

Hernández, P. A., Padrón, E., Melián, G. V., Pérez, N. M., Padilla, G., Asensio-Ramos, M., Di Nardo, D., Barrancos, J., Pacheco, J. M., and Smit, M.: Gas hazard assessment at Puerto Naos and La Bombilla inhabited areas, Cumbre Vieja volcano, La Palma, Canary Islands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7705, https://doi.org/10.5194/egusphere-egu22-7705, 2022.

How to cite: Rodríguez, N., Asensio-Ramos, M., Melián, G. V., Amonte, C., Álvarez Díaz, A. J., González Pérez, A. M., Rodríguez, F., Padilla, G. D., Barrancos, J., D'Auria, L., Hernández, P. A., and Pérez, N. M.: CO2 hazard mapping in the buildings of La Bombilla and Puerto Naos (La Palma, Canary Islands) using of alkaline traps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3643, https://doi.org/10.5194/egusphere-egu23-3643, 2023.

In the aftermath of the 2021 eruption of Cumbre Vieja volcano, a network of four low-cost air sensors was installed at four different sites in the village of Puerto Naos in La Palma, Canary Islands. These sensors measure CO₂, temperature, and relative humidity every one minute.

The measurements made between January and December of 2022 showed that all sensors frequently overpassed the 0.5 vol.%, defined by several organizations as the Permissible Exposure Limit (PEL) for safety in work environments. In addition, three of the sensors reached the instrument’s full scale (4.0 vol. %), a concentration above the STEL (short-term exposure limit) that can cause symptoms such as headache, weakness and breathing acceleration.

The Lomb-Scargle power spectral density estimate, obtained applying the plomb function of Matlab R2021a to the data, revealed diurnal cycles on the atmospheric CO₂ concentration time series in all monitored sites. All sites showed at least one cycle per day, with two of the sites having two cycles per day. One site, with an outdoor sensor, showed three cycles per day during the monitored period. Air temperature and relative humidity at the same sites showed similar periodicity, suggesting that the gas concentrations are correlated with the meteorological parameters. These observations, as far as we know, are the first to highlight the cyclic behaviour on volcanic air CO₂ time series.

This work was partially funded by FCT – Fundação para a Ciência e Tecnologia, under project SONDA - Synchronous Oceanic and Atmospheric Data Acquisition (PTDC/EME-SIS/1960/2020), and VOLRISKMAC II - Fortalecimiento de las capacidades de I+D+i para el desarrollo de la resiliencia frente a emergencias volcánicas en la Macaronesia (INTERREG MAC2/3.5b/328).

How to cite: Oliveira, S., Viveiros, F., Pacheco, J., Henriques, D., Moutinho, A., Pèrez, N., and Hernández, P.: Periodical behaviour of air CO2 time series after Cumbre Vieja volcanic eruption, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7546, https://doi.org/10.5194/egusphere-egu23-7546, 2023.

Radon (²²²Rn) is a noble gas that results from the radioactive decay chain of ²³⁸U. As the only gaseous element of this decay chain is the element with more mobility and can be released from the rocks and soils into the atmosphere. In outdoor environments the presence of this gas normally does not pose a problem for public health, however when it accumulates inside buildings it can represent a threat for human health. Being a radioactive gas, the radiation released can damage the lung cells and, in certain conditions, the damage can be so severe that can lead to the development of lung cancer.

The studied areas are located at S. Miguel and S. Jorge volcanic island located in the Azores archipelago. Two different volcanic environments were considered in this study, namely, a trachytic polygenetic volcano and basaltic rift zones. The trachytic polygenetic volcano selected was Furnas Volcano located at S. Miguel Island. Furnas Volcano is well known by its important soil diffuse degassing (CO₂ and ²²²Rn), fumarolic fields, thermal and CO₂-rich waters. Two basaltic rift systems were selected, the Picos Volcanic System located in S. Miguel Island and the Manadas Volcanic System located at S. Jorge Island. No important visible degassing was known in both volcanic systems.

At Furnas Volcano, the radon measurements were performed in buildings located at Furnas Village with maximum values of 14864 Bq/m³. In the basaltic rift zones, measurements were performed at Ponta Delgada City located at Picos Volcanic System and at Velas, Toledo, and Santo Amaro villages located at Manadas Volcanic System. In Ponta Delgada the maximum value reached 3717 Bq/m³ and in the Manadas Volcanic System the maximum value was measured at Velas reaching 1885 Bq/m³. Spectral Analysis and Multivariate Regression Analysis were applied to the data obtained to evaluate variables that may interfere with the radon emission as well as cyclic behaviour.

Despite the geological differences between the two volcanic environments considered in this study, the maximum values measured in all the volcanic systems were above the 300 Bq/m³, limit proposed by the Portuguese law for human exposure.  As so, this work enhances the importance of performing indoor measurements in volcanic environments, even in areas where lower values would be expected.

How to cite: Silva, C., Viveiros, F., and Ferreira, T.: Radon (222Rn) in volcanic islands (Azores): Implications for public health, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5940, https://doi.org/10.5194/egusphere-egu23-5940, 2023.

Secondary manifestations of volcanism found out at Fogo Volcano (São Miguel Island, Azores) comprise essentially hydrothermal fumaroles, thermal and cold-CO₂ rich springs, as well as diffuse degassing areas. Visible emissions are essentially located on the north flank of the volcano and are associated to the general NW-SE faults of the Ribeira Grande graben. Diffuse degassing surveys aiming at measuring the soil CO₂ concentration at about 50 cm depth were carried out in the north flank of the volcano in the last 20 years and anomalous CO₂ was associated to NW-SE trends, coincident with the graben faults. Soil CO₂ flux surveys, through the accumulation chamber method, were carried out during summer-autumn 2022 in the areas surrounding the three main fumarolic fields: Caldeira Velha, Caldeiras da Ribeira Grande, and Pico Vermelho. A total of 1207 sites were sampled in an area with about 1 km². Interpolated data (sequential Gaussian simulation) together with the Graphical Statistical Approach estimated a value around 95.5 t/d for the CO₂ emitted to the atmosphere. Main anomalous CO₂ fluxes are correlated with temperature anomalies and DDS (Diffuse Degassing Structures) show general NW-SE orientations, suggesting the correlation between degassing and tectonic structures in the study site, similarly to the observed in previous studies. This work contributes not only to the estimation on the total carbon-budget, but may also be a valuable tool to identify potential anomalies related with unrest of the volcanic system.

This work was partially funded by FCT – Fundação para a Ciência e Tecnologia, under project MAGAT - From MAGma to the ATmosphere - uma contribuição para desenvolver a próxima geração de sensores geoquímicos para a monitorização em tempo real do movimento do magma em profundidade (CIRCNA/OCT/0016/2019).

How to cite: Viveiros, F., Bettencourt, G., Cordeiro, A., Andrade, C., and Silva, C.: Estimation of soil CO2 flux emissions at Fogo Volcano (São Miguel Island, Azores), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5705, https://doi.org/10.5194/egusphere-egu23-5705, 2023.

During and after the end of the 2021 Tajogaite eruption (La Palma, Canary Islands), anomalous CO₂ degassing has been detected in the neighborhoods of La Bombilla and Puerto Naos, located around 5 km distance southwestern of the 2021 Tajogaite eruption vents. The aim of this study is to determine the indoor air quality of the houses of the aforementioned neighborhoods. For that purpose, from August 11 to October 24, 2022, air samples were taken, for further analysis, from indoors of 10 locations in Puerto Naos, on a weekly basis. In addition, on September 22, 2022, a discrete survey of the indoor ambient air was carried out in 10 houses of La Bombilla, consisting on in-situ measurements and gas sampling for further analysis.

Gas samples were taken for a complete geochemical characterization (i.e., He, Ar, Ne, H₂, N₂, O₂, CH₄, CO contents) by micro-gas chromatography (micro-GC) and quadrupole mass spectrometry (QMS) and, as well as for carbon isotopic analysis of the CO₂ (δ¹³C-CO₂) by isotopic ratio mass spectrometry (IRMS). In-situ measurements of CO₂, O₂, ²²²Rn, ²²⁰Rn, H₂S and Hg⁰ were conducted in La Bombilla with and without natural ventilation.

National Health Systems in the European Union reflect that the upper limit of the acceptable CO₂ concentration range for long-term exposure in the indoor ambient air of buildings for residential use should be of the order of 1,000-1,200 ppm to guarantee people health. The concentrations of CO₂ registered in the indoor ambient air of the 10 houses of La Bombilla determined by the in-situ measurements showed relatively high values -above 5,000 ppm- even reaching a maximum of 183,900 ppm in conditions without natural ventilation. In these conditions of absence of ventilation, a certain displacement of O₂ was observed, which dropped to 18.7% in the worst case. Under conditions with natural ventilation for a period of 2 hours, the range of CO₂ concentration fell to a range between 1,050 and 14,200 ppm and the O₂ concentration registered was 20.9%. These results reflect that natural ventilation, and even more forced ventilation, would contribute to reduce CO₂ concentration in the ambient air inside buildings. Regarding the results of the indoor gas samples analysis from Puerto Naos, the CO₂ concentration and the δ¹³C-CO₂ mean values ranged from 1,190 to 230,952 ppm and -7.9 to -4.8‰ vs. VPDB, respectively. These results of the chemical and isotopic composition of the indoor ambient air of Puerto Naos and La Bombilla demonstrate the importance of these studies to monitor and manage these silent hazards that pose a threat to the population and restrict access to their houses.

How to cite: Rodríguez, F., Asensio-Ramos, M., Melián, G. V., Hernández, P. A., Amonte, C., Álvarez Díaz, A. J., González Pérez, A. M., Calvo, D., Padilla, G. D., Barrancos, J., Ortega, V., Cabrera, I., Padrón, E., D'Auria, L., and Pérez, N. M.: Chemical and isotopic composition of the indoor ambient air of Puerto Naos and La Bombilla, La Palma, Canary Islands, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6431, https://doi.org/10.5194/egusphere-egu23-6431, 2023.

Hydrothermal areas are potentially hazardous to humans, as volcanic gases such as carbon dioxide (CO₂) and radon (²²²Rn) are continuously released from soil diffuse degassing. Even though many studies have established an association between exposure to anthropogenic air pollution and changes in lung function and, that radon exposure is estimated to be the second leading cause of lung cancer, the health risks of exposure to these elements in hydrothermal areas remain poorly known.

We investigated the association of chronic exposure to volcanogenic soil diffuse degassing with restrictive and chronic obstructive (COPD) respiratory defects and with DNA damage. A cross-sectional study was designed to evaluate the human lung function and the DNA damage in the buccal epithelial cells of individuals chronically exposed to carbon dioxide and indoor radon in a volcanic area (Furnas volcano, Azores, Portugal) with a hydrothermal system. A total of 150 individuals inhabiting the hydrothermal area (study group) and a reference group of 383 individuals inhabiting a non-hydrothermal area were considered to study the lung function; to study the DNA damage, buccal epithelial cells were collected from a sub-selection of 33 individuals inhabiting the volcanic area and from 49 individuals inhabiting the non-hydrothermal area. Lung function [FEV₁ (forced expiratory volume in 1 sec), FVC (forced vital capacity) and Tiffeneau-Pinelli index (FEV₁/FVC ratio)] were measured by spirometry test. Indoor radon was measured with Ramon 2.2 detectors. DNA damage was measured by micronucleus cytome assay. Data were analyzed with logistic regression models, adjusting for confounding factors (age, gender, body mass index, smoking status, and asthma). 

The prevalence of restrictions in the study group was significantly higher than in the reference group (10% vs. 2.87%, respectively; p<0.001). Similarly, the prevalence of COPD in the study group was significantly higher than in the reference group (33% vs. 12%, respectively; p<0.001). Chronic exposure to volcanogenic soil diffuse degassing was significantly associated with a higher prevalence of respiratory restrictions and exacerbation in COPD severity. The risk of having a restrictive respiratory defect was significantly increased in the study group (3.55 times higher) when compared to the reference one. Similarly, the risk of COPD exacerbation was significantly increased in the study group (3.96 times higher). Indoor radon concentration correlated positively with the frequency of micronucleated cells (rs=0.325, p=0.003) and revealed to be a risk factor for the occurrence of micronucleated cells in the inhabitants of the hydrothermal area (RR= 1.71; 95% CI, 1.2–2.4; p=0.003).

These findings reinforce the need for further studies with human populations living in these areas and, may assist health officials in advising and keeping up with these populations to prevent and minimize the risk of respiratory diseases and DNA damage caused by genotoxic elements.

Keywords: Volcanic gases, volcanism, genotoxicity; micronuclei; biomonitoring.

How to cite: Linhares, D., Garcia, P., Viveiros, F., Silva, C., and Rodrigues, A.: Chronic exposure to volcanogenic carbon dioxide and radon: how does it affect lung function and DNA in oral epithelial cells of the inhabitants in hydrothermal areas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2652, https://doi.org/10.5194/egusphere-egu23-2652, 2023.

Volcanogenic air pollution studies and their effects on the respiratory system are still outnumbered by studies regarding the effects of anthropogenic air pollution, representing an unknown risk to human population inhabiting volcanic areas worldwide (either eruptive or non-eruptive areas).
This study was carried out in the Azorean archipelago of Portugal, in areas with active non-eruptive volcanism. The hydrothermal emissions within the volcanic complex of Furnas (São Miguel Island) are responsible for the emission of nearly 1000 tons of CO₂ per day, along with H2S, the radioactive gas –
radon, among others. Besides the gaseous emissions, metals (e.g., Hg, Cd, Al, Ni) and particulate matter are also released into the environment. We test the hypothesis whether chronic exposure to hydrothermal emissions causes pulmonary oxidative stress, using Mus musculus as a surrogate species. M. musculus were live-captured in: two villages with hydrothermal emissions and one village without any type of volcanic activity. Immunohistochemical evaluations were performed to access the level of pulmonary oxidative stress using an OxyIHC^TM Oxidative stress detection kit, and the detection of terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end-labeling (TUNEL) was used to evaluate apoptosis in lung tissues. Mice chronically exposed to hydrothermal emissions presented increased levels of oxidative stress and amount of apoptotic cells. We demonstrate, for the first time, the high oxidative stress potential in the lungs of mice chronically exposed to hydrothermal emissions. This study also highlights the Mus musculus as a useful bioindicator for future biomonitoring programs in these types of volcanic environments.

How to cite: Camarinho, R., Linhares, D., Garcia, P., and Rodrigues, A.: Chronic exposure to non-eruptive volcanic activity as cause of pulmonary oxidativestress and apoptosis in mice, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17321, https://doi.org/10.5194/egusphere-egu23-17321, 2023.